Abstract

Due to increasing interest to natural preservatives, many studies have been performed in recent years. Nisin peptide as a natural preservative is very interesting for the control of food pathogens and microorganisms of food spoilage. In this study antibacterial activity of nisin and its synergism in decreasing concentrations of common chemical preservatives like sodium nitrite and benzoic acid against standard bacteria of Staphylococcus aureus and Lysteria monocytogenes has been investigated. For this purpose, the MIC (minimum inhibitory concentration) of nisin peptide, sodium nitrite and benzoic acid were evaluated at different pH based on the dilution method. Results showed that these compounds have antibacterial activity against Staphylococcus aureus and Lysteria monocytogenes. MIC for nisin peptide, sodium nitrite and benzoic acid in Staphylococcus aureus, was 350, 200, 25 (ppm) respectively. These values were 100, 200, 10 (ppm) in Lysteria monocytogenes. It has been also shown that simultaneous use of nisin with chemical preservatives sodium nitrite and benzoic acid reduced MIC of these compounds against two strains of bacteria. This synergistic effect of nisin could reduce the use of chemical preservatives in food industry.